Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	$ 2,796	$ 894
Derivative liability, fair value, gross liability	2,687	982
Commodity Future [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	2,787	886
Derivative asset, fair value, gross liability	2,681	966
Commodity Option [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	5	8
Derivative asset, fair value, gross liability	0	3
Physical Purchase Contracts [Member] | Inventories [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	0	0
Derivative asset, fair value, gross liability	5	6
Foreign Currency Contracts [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	4	0
Derivative asset, fair value, gross liability	0	0
Foreign Currency Contracts [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative liability, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	$ 1	$ 7